source
To create the USB drive to install Windows Server 2019 on BIOS (MBR) systems.
Use PowerShell with Administrative priveleges:
# Define Path to the Windows Server 2019 ISO
$ISOFile = "C:\Temp\WindowsServer2019.iso"
# Get the USB Drive you want to use, copy the friendly name
Get-Disk | Where BusType -eq "USB"
# Get the right USB Drive (You will need to change the FriendlyName)
$USBDrive = Get-Disk | Where FriendlyName -eq "Kingston DT Workspace"
# Replace the Friendly Name to clean the USB Drive (THIS WILL REMOVE EVERYTHING)
$USBDrive | Clear-Disk -RemoveData -Confirm:$true -PassThru
# Convert Disk to MBR
$USBDrive | Initialize-Disk -PartitionStyle MBR
# Create partition primary and format to NTFS
$Volume = $USBDrive | New-Partition -UseMaximumSize -AssignDriveLetter | Format-Volume -FileSystem NTFS -NewFileSystemLabel WS2019
# Set Partiton to Active
$Volume | Get-Partition | Set-Partition -IsActive $true
# Mount ISO
$ISOMounted = Mount-DiskImage -ImagePath $ISOFile -StorageType ISO -PassThru
# Driver letter
$ISODriveLetter = ($ISOMounted | Get-Volume).DriveLetter
# Copy Files to USB
Copy-Item -Path ($ISODriveLetter +":\*") -Destination ($Volume.DriveLetter + ":\") -Recurse
# Dismount ISO
Dismount-DiskImage -ImagePath $ISOFile